This invention relates to a process for the suspension (co)polymerization of vinyl chloride in the presence of a radical initiator and at least two suspension stabilizers.
The suspension polymerization of vinyl chloride is generally known in the art. One may, for example, refer to British Pat. Nos. 1,524,492 and 1,541,386. The two patent specifications describe the use of a water-soluble polyvinyl alcohol in combination with a partially hydrolyzed polyvinyl acetate which is itself only poorly soluble or insoluble in water. Also, as a pure product, the partially hydrolyzed polyvinyl acetate is generally difficult to handle. Thus, in actual practice, such a suspension stabilizer has been mostly used as a solution in methanol. However, for some applications, the presence of methanol is not desirable.
British Pat. No. 1,543,431 describes a stabilizer system for the polymerization of vinyl chloride which is a combination of a methyl hydroxypropyl cellulose and a polyvinyl alcohol which has an acetate content of 61.5 to 70.5% by weight.